1. Field of the Invention
The present invention relates to a gimbal spring for supporting a slider which carries a magnetic transducer over a rotating magnetic medium. More specifically, this invention relates to a gimbal spring that provides a conduction path from the slider to the gimbal spring for electrostatic discharge.
2. Description of the Prior Art
A gimbal spring is a critical element in a magnetic disk drive unit. Within the disk drive an actuator arm supports a slider which carries a magnetic transducer close to a rotating magnetic disk. The gimbal spring is positioned between the actuator arm and the slider. The gimbal spring resiliently supports the slider and allows it to move vertically and to pitch and roll while it follows the topography of the rotating disk. Typically, the gimbal spring is riveted to the actuator arm and is connected to the slider by an adhesive.
The adhesive connection tends to insulate electrically the slider from the gimbal spring. As the slider follows the topography of the rotating disk, electrostatic charge accumulates on the slider and impedes performance of read and write operations between the transducer and the magnetic disk. An electrical conduction path between the slider and the gimbal spring is needed to prevent the accumulation of charge by grounding the slider to the gimbal spring.
Attempts to provide a conduction path have included using a conductive epoxy as an adhesive. Conductive epoxy includes a mix of an epoxy and a conductive filler such as silver particles. These particles are in contact with one another and create a conductive chain between the slider and the gimbal spring. In order to create the conductive chain, the particles must be relatively large in size. As the gimbal spring is bonded to the slider, these large particles can prevent a parallel bond between the slider and the gimbal spring. In other words, the slider surface will not be parallel to the gimbal spring surface. This is a disadvantage because accurate positioning of the transducer over individual data tracks on the rotating magnetic disk is essential to disk drive performance. In addition, the filler particles used in conductive epoxy reduce the overall bond strength of the epoxy. Therefore, it is preferable to use adhesives that do not contain fillers so the connection is a strong, parallel bond.
Another method of providing a conduction path is to secure the slider to the gimbal spring with a nonconductive adhesive and then form conductive bridges which bridge the nonconductive adhesive connection. These conductive bridges can be formed by applying conductive epoxy across the adhesive connection. Forming each conductive bridge creates an extra manufacturing step and increases production cost.
The prior art lacks a simple method of grounding the slider across the adhesive connection between the slider and the gimbal spring.